1. Field of the Invention
The present invention generally relates to septic tank sewage disposal systems and more particularly the drain field by which an effluent is disposed of below ground surface in a well known manner with the invention more particularly relating to an assembly of porous concrete blocks having tension rods extending through and connecting a group of blocks into a module to facilitate assembly and installation of the septic tank disposal system.
2. Description of the Prior Art
Septic tank sewage disposal systems basically include a septic tank and a drain field which includes a series of trenches or ditches dug into the soil at a predetermined depth, a quantity of gravel, sand or the like in the bottom of the trenches and drain tile disposed therein and communicated with the septic tank. The drain tiles are, in some instances, spaced apart slightly to form discharge slots for liquid effluent so that such effluent will discharge into the soil surface. One of the problems which occurs in this type of installation is the incapability of the soil to absorb effluent and clogging of the drain field by solid organic material. Most localities require that the soil pass a percolation test before a septic tank sewage disposal system can be installed.
Efforts have been made to improve such systems with U.S. Pat. No. 3,422,010 issued Jan. 14, 1969, disclosing a different type of arrangement in which a plurality of concrete blocks of porous material are assembled in sealed end-to-end relation by use of mortar with each of the blocks including multiple passageways therein which, when aligned, provide a drain field in which effluent is discharged through the blocks throughout the length of the drain field and throughout the periphery of the blocks due to the multiple passageways therethrough in which the effluent will pass back and forth through the aligned blocks.
When installing this type of system, it is difficult to apply mortar to the ends of the blocks and orient the blocks in end-to-end aligned relation when at the bottom of a relatively narrow trench. In addition to being quite time consuming, the installation requires considerable expertise and requires substantial manual handling and manipulation of the blocks, all of which render the installation of this type of block relatively inefficient and quite costly.